1. Technical Field
The present invention relates to a common mode filter, and more particularly, to a common mode filter having a protecting layer and a method of manufacturing the same.
2. Description of the Related Art
With the development of technology, electronic devices such as mobile phones, household appliances, PC, PDA, LCD, and the like, are converted from an analog type to a digital type, and are have higher speed due to an increase in data amount. For this reason, USB 2.0, USB 3.0, and a high-definition multimedia interface (HDMI) as high-speed signal transmission interfaces have been widely supplied, and also have been used in many digital devices such as personal computers and digital high-definition televisions.
Theses interfaces employ a differential signal system of transmitting a differential signal (a differential mode signal) by using a pair of signal lines, unlike a single-end signal transmission system generally used for a long time.
Therefore, a common mode filter is generally used to remove common mode noise generated from high-speed differential signal lines and the like. Here, the common mode noise is noise generated from the differential signal lines, and the common mode filter removes this noise that cannot be removed by the existing EMI filter
Referring to Japanese Patent Laid-Open Publication No. 2012-015494, the common mode filter of the related art is generally composed of a lower magnetic layer, an upper magnetic layer, and an insulating layer provided therebetween while having coil electrodes therein. In addition, external electrode terminals for connecting the coil electrodes to an external circuit are formed in a post type while passing through the upper magnetic layer.
Generally, the upper magnetic layer is filled with a paste, sol, gel, or the like, while having low density. In this case, the upper magnetic layer is vulnerable to external impact due to weak durability thereof.
In addition, bubbles are contained therein at the time of charging, which may cause permeation of external moisture and the like into the device, resulting in deteriorating characteristics thereof.